1. Field
The present general inventive concept relates to a toner to develop an electrostatic charge image (hereinafter, referred to as “toner”) which may be used in an image forming apparatus using an electrophotographic process, such as a copier, a printer, a facsimile, and the like.
2. Description of the Related Art
With advances in electrophotographic fields, an electrophotographic process is used in copiers and printers and for printing applications, and demands for a high-speed, highly reliable, high quality device are on the rise. Accordingly, high gloss properties, durability corresponding to high speed, and long lifetime of a toner have emerged as important factors. In particular, measures to save energy and reduce environmental load have recently become more necessary. One of these measures is to reduce power consumption in a fixing process requiring a large amount of power consumption in the electrophotographic process.
As one of the methods of improving fixability of a toner, a technology to reduce a glass transition temperature or a molecular weight of a binder resin is generally used. When the glass transition temperature of the binder resin is too low, however, blocking of a toner occurs or a storage stability of a fixed image is deteriorated, and thus, it is difficult to obtain a low-temperature fixable toner by using only a method of reducing a glass transition temperature of a binder resin.
In addition, a toner including a crystalline resin is disclosed, as is disclosed in Japanese Patent Application Publication No. hei 1-35454. A crystalline resin has a melting point and is melted at that melting point or a higher temperature, and thus, the addition of the crystalline resin to a binder resin is an effective means to improve fixability of a toner. As a binder resin, a polyester resin is used in terms of improvement in fixability and resin strength. Although a styrene-acrylic resin or an epoxy-based resin may also be used, a polyester resin with high gloss properties may be used to design a resin having desired melting properties. In particular, a crystalline polyester resin having a low melting temperature may be used to obtain low-temperature fixability.
Meanwhile, with recent miniaturization of printers, developers or fixing systems have been miniaturized and stress on a toner has increased. Moreover, under certain use conditions such as a temperature of more than 30° C. (e.g., during summer), a printer main body or a toner itself is exposed to high-temperature conditions, and thus, when 10 or more sheets of paper are continuously printed, time is required to cool the melted toner after a toner including a crystalline polyester resin is fixed. Thus, the fixed image is likely to be nonuniformly formed due to the remaining heat during the fixing process. Accordingly, gloss properties may be deteriorated, or a toner may be excessively heated so that the toner permeates into paper more than is required, resulting in degradation of the image quality. In addition, a toner may be blocked by stress applied inside a developer or an internal temperature of a printer.